1. Field of the Invention
This invention relates generally to fuel injection systems for gas turbine engines and, more particularly, to a fuel injection system which provides a greater density of fuel injector nozzles within the combustion chamber of a gas turbine engine.
2. Description of the Prior Art
As is well known, gas turbine engines typically include a rotor and a turbine wheel rotatable about a generally horizontal axis. Not infrequently, an annular combustor surrounds the axis and is provided with a plurality of angularly spaced fuel injectors whereby fuel is injected into the combustor to be burned and ultimately directed at the turbine wheel to spin the same. At a location that is usually external of the combustor, a ring-like manifold is utilized as a fuel manifold that interconnects the various fuel injectors. Because the rotational axis of the compressor and turbine wheel is typically horizontal, the ring-like manifold lies in a vertical plane.
A typical conventional construction of a fuel injection system for a gas turbine engine is disclosed in U.S. Pat. No. 4,862,693. In that patent, a generally toroidal shaped manifold is provided with a plurality of spaced injectors which are joined by a plurality of rigid tube sections.
In another construction as disclosed in U.S. Pat. Nos. 4,903,478 and 5,036,657, a fuel injection system for use in the combustor section of a gas turbine engine comprises a first and a second plurality of fuel nozzles which are in fluid supply communication with first and second fuel manifolds, respectively. The manifolds are supplied with fuel by first and second fuel lines, respectively, which in turn are supplied from a fuel control. A portion of the fuel nozzles is interruptible in response to a predetermined gas turbine engine parameter or condition. In one instance, the engine parameter is the fuel to air ratio and in another instance, the engine condition is descent as indicated by the power setting of the gas turbine engine. In still another instance, the fuel control may be controlled by a digital electronic computer.
The technical requirements for the latest generation of gas turbine engines call for ever higher combustor efficiencies. A very important factor for achieving increased efficiency is the proximity of the fuel nozzles within the combustor. At the same time it is necessary to place the fuel nozzles on substantially the same pitch circle which necessitates decreased distance between the associated fittings of adjoining fuel nozzles. A point is reached at which further reduction in the distance between fuel nozzles along the pitch circle can no longer be accommodated using conventional construction techniques. It was to satisfy this requirement and, in light of the prior art as indicated above, that the present invention has been conceived and is now reduced to practice.